AD9937 データシートの表示（PDF） - Analog Devices

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AD9937

CCD Signal Processor with Precision Timing™ Generator

Analog Devices 

AD9937

TERMINOLOGY

Differential Nonlinearity (DNL)

An ideal ADC exhibits code transitions that are exactly 1 LSB

apart. DNL is the deviation from this ideal value. Thus, every

code must have a finite width. No missing codes guaranteed to

10-bit resolution indicates that all 1024 codes must be present

over all operating conditions.

Peak Nonlinearity

Peak nonlinearity, a full signal chain specification, refers to the

peak deviation of the output of the AD9937 from a true straight

line. The point used as zero scale occurs 1/2 LSB before the first

code transition. Positive full scale is defined as a level 1 1/2 LSB

beyond the last code transition. The deviation is measured from

the middle of each particular output code to the true straight line.

The error is then expressed as a percentage of the 2 V ADC full-

scale signal. The input signal is always appropriately gained up

to fill the ADC’s full-scale range.

Total Output Noise

The rms output noise is measured using histogram techniques.

The standard deviation of the ADC output codes is calculated

in LSB and represents the rms noise level of the total signal

chain at the specified gain setting. The output noise can be

converted to an equivalent voltage, using the relationship

( ) 1 LSB = ADC Full Scale 2N codes

where N is the bit resolution of the ADC. For the AD9937, 1 LSB

is 1.95 mV.

Power Supply Rejection (PSR)

The PSR is measured with a step change applied to the supply

pins. This represents a very high frequency disturbance on the

AD9937’s power supply. The PSR specification is calculated

from the change in the data outputs for a given step change in

the supply voltage.

EQUIVALENT CIRCUITS

AVDD

R

AVSS

AVSS

Figure 1. CCDIN

DATA

DVDD

DRVDD

TRISTATEOUT

DOUT

DVDD

330⍀

DVSS

Figure 3. Digital Inputs

RS,

H1 (A–D),

H2 (A, B)

HVDD1, HVDD2,

OR RSVDD

ENABLE

OUTPUT

DVSS DRVSS

Figure 2. Digital Data Outputs

HVSS1, HVSS2,

OR RSVSS

Figure 4. H1(A–D), H2(A, B), and RS Drivers

REV. 0

–7–

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